Apparatus for thermal melting process and method of thermal melting process

ABSTRACT

Provide is an apparatus for thermal melting processes that is capable of directly cooling the process object without requiring a separate cooling plate. 
     The apparatus for thermal melting process according to the present invention is an apparatus  1  for thermal melting process that thermally melts objects  100  including solder in an atmosphere containing carbonic acid vapor, and the hand part  4  for carrying and transferring the thermally melted process objects  100  is used as a cooling plate as well.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Phase filing of PCT Application No.PCT/JP2010/064299 filed Aug. 27, 2010 and claims priority to JapanesePatent Application Number 2009-196687 filed Aug. 27, 2009 and JapanesePatent Application 2009-254255, filed Nov. 5, 2009, the disclosure ofwhich is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to an apparatus for thermal meltingprocess and a method of thermal melting process for thermally meltingprocess objects including solder.

BACKGROUND TECHNOLOGY

Various thermal melting apparatuses such as solder processingapparatuses and solder ball forming apparatuses for thermally meltingvarious process objects including solder have been used recently. Morespecifically, certain thermally melting process apparatuses have beenused for enabling solder processing and solder ball forming processusing carbonic acids such as formic acid instead of flux (PatentDocuments 1 and 2).

It is required for these thermally melting process apparatuses toshorten the time between melting to cooling from the standpoint ofimproving the speed of the operation. Based on this standpoint, theapparatus disclosed by Patent Document 1 provides a cooling plate in aliftable manner beneath the heating plate having a heating means so thatthe cooling plate can be lifted to contact the hot plate in order toforce-cool the substrate being soldered.

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: Publication of Japanese Patent Application    11-233934-   Patent Document 2: Publication of Japanese Patent Application    2001-244618

SUMMARY Problems to be Solved by the Invention

However, in the apparatus for thermally melting process mentioned above,the cooling plate is only used to cool the hot plate where heating meansis provided by closely contacting with it, not cooling the processobject itself such as a substrate being soldered by closely contactingwith it.

Therefore, this thermal melting process of the prior art has a problemthat it is only good for cooling the process object indirectly via thehot plate, and is not capable of directly cooling the process object.Moreover, it has a problem that a separate cooling plate has to beinstalled in a movable manner in addition to having a transfer means totransfer the process object in and out of the chamber.

Therefore, the object of the present invention is to provide anapparatus for thermal melting processes that is capable of directlycooling the process object without requiring a separate cooling plate.

Means for Solving Problems

The apparatus for thermal melting process according to the presentinvention is an apparatus for thermal melting process that thermallymelts objects including solder in an atmosphere containing carbonic acidvapor, and is characterized in that a hand part that is used fortransferring the thermally melted process objects is used as a coolingplate as well.

The method for thermal melting process according to the presentinvention is characterized in that it comprises a step of thermallymelting a process object including solder in an atmosphere containingcarbonic acid vapor, and a step of transferring the thermally meltedprocess object on the hand part that is also used as a cooling plate aswell.

Effect of the Invention

According to the present invention, it is capable of rapid cooling andhence improves productivity because of accelerated production speed incomparison against a case of indirectly cooling the process object via ahot plate equipped with a heating means.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a schematic cross-sectional view of the apparatus forsoldering process according to the first embodiment of the presentinvention.

FIG. 2 shows a plan view (A) and A-A cross-sectional view (B) of thehand part of the apparatus for soldering process of FIG. 1.

FIG. 3 is a schematic cross-sectional view showing a soldering processby means of the apparatus for soldering process of FIG. 1.

FIG. 4 is a schematic cross-sectional view of a process that followsthat of FIG. 3.

FIG. 5 is a schematic cross-sectional view of a process that followsthat of FIG. 4.

FIG. 6 is a schematic cross-sectional view of a process that followsthat of FIG. 5.

FIG. 7 is a schematic cross-sectional view of a process that followsthat of FIG. 6.

FIG. 8 is a schematic cross-sectional view of a process that followsthat of FIG. 7.

FIG. 9 is a schematic cross-sectional view of a process that followsthat of FIG. 8.

FIG. 10 is a diagram showing temperature rise/fall characteristics bymeans of the apparatus for soldering of FIG. 1.

FIG. 11 is a diagram showing temperature rise/fall characteristics bymeans of a comparative apparatus for soldering.

FIG. 12 is a diagram showing the temperature distribution measuringpoints related to the temperature rise/fall characteristics of FIG. 10and FIG. 11.

FIG. 13 is a diagram showing the process condition in measuring thetemperature rise/fall characteristics of FIG. 10 and FIG. 11.

FIG. 14 is a diagram showing the temperature rise/fall characteristicsof the apparatus for soldering process of FIG. 1 in case when theprocess object is handed over while maintaining the heating condition.

FIG. 15 is an internal top view of an apparatus for soldering processaccording to a second embodiment.

FIG. 16 is a diagram showing an example of the temperature rise/fallcharacteristics of a variant case of the present invention.

WORKING CONFIGURATION OF INVENTION First Embodiment

The first embodiment of the present invention will be described belowwith reference to the accompanying drawings. In describing the drawings,identical elements will be identified by identical codes in order toavoid duplicating descriptions. The scaling factors of the drawings mayvary from those of the actual components because of intentionalexaggerations for the sake of explanations.

FIG. 1 shows the first embodiment wherein the apparatus for thermalmelting process according to the present invention is applied to anapparatus for soldering process. The solder processing apparatus 1 has afirst chamber 2 and a second chamber 3, as well as a hand part 4 thatcarries thereon and transfers between the chambers a substrate to besoldered, i.e., the process object, which also serves as a coolingplate.

Here, the first chamber 2 and the second chamber 3 are connected via agate valve 5 that opens and closes as needed. By closing the gate valve5, the first chamber 2 and the second chamber 3 can be isolated fromeach other by a plate-like shield member that forms a part of the gatevalve 5. Also, by opening the gate valve 5, the first chamber 2 and thesecond chamber 3 can conduct with each other while maintaining thesealing state of the first chamber 2 and the second chamber 3 from theoutside. Here, for example, it is possible to realize such a function ofthe gate valve 5 as described above by sliding the shield member thatforms a part of the gate valve 5 via a sealing member 55 to the insideor outside of the first chamber 2 or the second chamber 3. Such asealing member can be constituted using, for example, an O-ring. Thefirst chamber 2 serves as a processing chamber for soldering a substrate100 to be soldered, i.e., an object of processes including soldering,and the second chamber 3 serves as a load-lock chamber for loading thesubstrate 100 to be soldered. The substrate 100 to be soldered can be apair of chips at least one of which has a plurality of solder bumpsformed on its surface, wherein a flip chip bonding process is executedfor jointing the pair of chips in such a manner that they are laminatedvia each other's solder bumps or via solder bumps with electrodes as thesoldering process. In other words, in case the flip chip bonding processis employed, solder bumps are formed on the surfaces of both the firstchip and the second chip, so that the first chip and the second chip aresoldered together, or solder bumps are formed on the surface of thefirst chip while electrode parts are formed on the surface of the secondchip, so that the first chip and the second chip are soldered togethervia the solder bumps of the first chip and the electrode parts of thesecond chip.

Although a case of soldering both the first chip and the second chip wasdescribed in the above, other cases can be considered as well; forexample, a case of soldering together a chip and a wafer on the surfaceof both of which a plurality of solder bumps is formed, or a case ofsoldering a plurality of wafers on the surface of which a plurality ofsolder bumps is formed.

<On Air Supply/Exhaust System>

First, let us describe the air supply/exhaust system to be connected tothe first chamber 2 and the second chamber 3. The first chamber 2 andthe second chamber 3 are each connected to an exhaust pump (vacuum pump)8 via valves 6 and 7 respectively. The exhaust pump 8 is an exhaustmeans for the purpose of pressure reduction in the first chamber and thesecond chamber. In the present embodiment, only one exhaust pump 8 isprovided as a means of exhausting the first chamber 2 and the secondchamber 3, it can also be configured in such a way of having anindependent exhaust pump provided for each of the chambers 2 and 3.

The first chamber 2 is connected via a valve 10 to a carbonic acid vaporsupply system (carbonic acid supply means) 9 that makes it possible tosolder without flux. The carbonic acids that can be used here includeformic acid, acetic acid, propionic acid, butyric acid, valeric acid,capronic acid, enanthic acid, caprylic acid, pelargonic acid, oxalicacid, malonic acid, succinic acid, acrylic acid, salicylic acid, andlactic acid.

The carbonic acid vapor supply system 9 introduces carbonic acid gasmixed with carrier gas such as reducing gas like hydrogen or carbonmonoxide as well as inert gas like nitrogen into the first chamber. Thecarbonic acid vapor supply system 9 has a sealed container 11 containingliquid carbonic acid, and the sealed container 11 is connected to acarrier gas supply tube 13 that supplies carrier gas via a valve 12. Thecarrier gas supply tube 13 is connected to a bubbling part 14 forcausing bubbles (bubbling) inside the container 11. A heater can beprovided in the vicinity of the container 11 to warm the carbonic acidliquid. The heater is intended to keep the carbonic acid liquid at acertain temperature. Thus, by using the carrier gas in addition, it ispossible to make it easier for the carbonic acid vapor to be introducedinto the first chamber 2, and to make it possible to prevent thecarbonic acid not yet fully evaporated from adhering to the processobject to develop a residue.

It is also possible, different from the present embodiment, to introducethe carbonic acid vapor into the first chamber 2 without using thecarrier gas by communicating the sealed container 11 containing thecarbonic acid liquid with the first chamber 2. It is also possible toconfigure in such a manner as to mix the carrier gas with the carbonicacid liquid in the midway of communicating the sealed container 11containing the carbonic acid liquid with the first chamber 2. In such acase, the evaporation amount depends on the gas pressure inside thefirst chamber 2.

It is also possible to configure in such a manner as to provide acarbonic acid heating means (not shown) for heating carbonic acid tocause it evaporate inside the first chamber 2 and supply carbonic acidliquid to the carbonic acid heating means inside the first chamber via asupply tube (not shown). In this case, the carbonic acid heating meanscauses the liquid carbonic acid to be heated to evaporate inside thefirst chamber 2, thus to provide carbonic acid vapor atmosphere.

Next, let us describe the carbonic acid collection part. The solderprocessing apparatus 1 of the present embodiment has a carboniccollection part (collection mechanism) 15 for collecting the evaporatedcarbonic acid provided or attached to the suction or exhaust side of theexhaust pump 8. The carbonic acid collection part 15 can be a filterattached to the suction or exhaust side of the exhaust pump 8, or ascrubber attached to the exhaust side. A filter of a neutralizing typefilter utilizing alkaline solid substance consisting of a mixturecontaining Ca(OH)2 etc., or a thermal cracking type filter thatthermally cracks carbonic acid can be used as the filter in this case.Other filters, such as an adhesion type filter utilizing a molecularsieve to capture carbonic acid or a catalytic reaction type filterutilizing catalytic cracking reactions, can also be used for thispurpose. On the other hand, scrubbers such as a type of scrubber thatneutralizes carbonic acid in a liquid treatment, or a type of scrubberthat collects evaporated carbonic acid by dissolving it into a solution,can be used for this purpose. The type of scrubber that collectsevaporated carbonic acid by dissolving it into a solution has aconfiguration in which a first exhaust tube connected to the exhaustside of the exhaust pump is inserted into the solution in a liquid tank,and a second exhaust tube is connected to the top of the liquid tank.

Moreover, a nitrogen supply tube 16 is connected to the first chamber 2via a valve 17 in order to replace (to purge) the inside with a nitrogenatmosphere, and another nitrogen tube 18 is connected to the secondchamber 3 via a valve 19 as well.

<On Heating Means>

Next, let us describe the heating means provided in the first chamber 2.

A hot plate 20 is provided inside the first chamber 2 as a heatingmeans. A substrate 100 to be soldered is carried on the top surface ofthe hot plate 20 and heated. However, it is also possible to place thesubstrate 100 to be soldered on the hot plate 20 via a tray plate 110made of metal, ceramic or other materials if a large number ofsubstrates to be soldered 100 is involved. FIG. 1 shows a case where thesubstrate 100 to be soldered is placed via the tray plate 110.Therefore, in the following descriptions, not only the substrate 100 tobe soldered but also the tray plate 110 is described as the processobject in some cases, for the sake of convenience of description.

The hot plate 20 can be configured with metal, ceramic and othermaterials attached with a heater, and the heater can be an electricresistance heater, e.g., a sheathed heater. However, it is morepreferable to form the hot plate 20 with a plate-like member consistingof carbon from the standpoint of improving corrosion resistance and heatthe process object by heating the hot plate 20 itself by running acurrent through the plate-like member consisting of carbon 20 itself.

<On Transfer Part>

Next, let us describe the transfer part of the apparatus for solderingprocess of the present embodiment.

A lid 21 is provided on the second chamber 3 for taking the processobject in and out. The solder processing apparatus 1 has a transfer part(transfer means) 22 that transfers the loaded process object between thefirst chamber 2 and the second chamber 3.

The transfer part 22 has a hand part 4 and a transfer mechanism(transfer means) 23 for transferring the hand part 4 freely. The “handpart” in the invention of this application means a part on which theprocess object is placed for transferring the process object. The handpart 4 is formed as a plate-like member in the present embodiment.However, it is not limited to the particular shape, but rather variousshapes can be adopted in the hand part 4. Further, in order to improveits cooling efficiency, the top surface of the hand part 4 is preferablyformed flat so that it can have a close contact with the bottom surfaceof the substrate 100 or the tray plate 110. The hand part 4 can be madeof metal, ceramic or other materials.

FIG. 2 shows an example of the hand part. The hand part 4 has acirculation path 24 for the cooling medium to be circulated. In the caseshown in FIG. 2, the circulation path can be provided inside the handpart 4. For example, it can be so configured for the hand part to have ahand part main body in which a groove is formed as the circulation pathand a lid part which is jointed to the hand part main body, so that thejointing of the hand part main body with the lid part completes thecirculation path. The circulation path 24 is preferably formed in such away that it meanders within a surface so that it can cool a wide rangeof the hand part 4. Contrary to the present embodiment, the circulationpath 24 can be attached outside to the bottom surface, i.e., opposite tothe surface on which the substrate 100 or the tray plate 110 is placed.The cooling medium that flows through the circulation path 24 can beeither liquid or gas. However, the medium should preferably be liquidfrom the standpoint of cooling efficiency, in particular, water ispreferable from the standpoint of ease of handling. An inlet port 25 andan outlet port of the circulation path 24 should preferably extend tothe outside of the second chamber via a flexible tube (not shown) and beconnected to an outside coolant circulation apparatus (not shown).

Such a hand part 4 is attached to the transfer mechanism 23. Thetransfer mechanism 23 moves the hand part 4 back and forth freelybetween the first chamber 2 and the second chamber 3. In FIG. 1, thetransfer mechanism 23 has rails 27 (27 a, 27 b, 27 c) and a transferstage 28 that is transferred over the particular rails 27 by means ofmotor power. The rails 27 has a first rail part 27 a located within thefirst chamber 2, the second part 27 b located within the second chamber3, and the third rail part 27 c located between them. The third railpart 27 c is attached to the top of the gate valve 5 and moves incoordination with the opening/closing motion of the gate valve 5 betweenthe first chamber 2 and the second chamber 3, and completes the overallrails 27 by connecting the first rail part 27 a with the second railpart 27 b while the gate valve 5 is open.

In addition, although the rails 27 and the transfer stage 28 are used toconstitute the transfer mechanism 23 in the present embodiment, thetransfer mechanism is not limited to such a case, but can be constitutedin various other mechanisms, including a single axis or multi-axes robotarm, so long as they are capable of transferring the hand part 4 betweenthe first chamber 2 and the second chamber 3.

Next, let us describe the lifting mechanism that lifts the processobject up and down inside the chamber 2 in order to deliver the processobject to the hand part 4. As shown in FIG. 1, the lifting mechanism 29is a mechanism for lifting the substrate 100 and the tray plate 110 upand down. The lifting mechanism 29 can lift the process objects such asthe substrate 100 and the tray plate 110 carrying the substrate 100upwards to separate them from the condition of being placed on the topsurface of the hot plate 20 (heating means). Alternatively, afterreceiving the process object at the condition of being separated fromthe hot plate 20, it can lower the process object until it is laid onthe top surface of the hot plate 20.

Although a case of using a stick-like lifting level to be used as thelifting mechanism 29 in the present embodiment, the invention is notlimited to it. So long as it is capable of moving up or downwards whilesupporting the process object, anything can be used as a liftingmechanism.

Next, let us describe the operation of the solder processing apparatus 1as constituted in such a manner as described above.

First, the lid 21 of the second chamber 3 is opened as shown in FIG. 3to load the process object, i.e., the substrate 100, into the secondchamber 3. In the present embodiment, a plurality of substrates 100carried on top of the tray plate 110 is loaded. The loaded tray plate110 is placed on the top surface of the hand part 4.

Next, the lid 21 is closed as shown in FIG. 4. The valves 6 and 7 openand the exhaust pump 8 is operated to evacuate the first chamber 2 andthe second chamber 3. The degree of vacuum can be arbitrarilydetermined, but should preferably be higher than 10000 Pa (≈80 Torr), ormore preferably higher than 10 Pa (≈8×10⁻² Torr). In the presentembodiment, the degree of vacuum is chosen to be 6.6 Pa (5×10⁻² Torr).

Next, the gate valve 5 is opened as shown in FIG. 5. The transfer part22 transfers the tray plate 110 from the second chamber 3 to the firstchamber 2. More specifically, the first rail part 27 a, the second railpart 27 b, and the third rail part 27 c are connected together tocomplete the rails 27 linked to the opening of the gate valve 5. Themotor power of the transfer stage 28 is turned on to transfer the handpart 4 to the first chamber 2 along the rails 27. The transfer stage 28continues to move until the hand part 4 becomes located above the hotplate 20. For example, the transfer stage 28 is shaped in such a mannerto stride over the hot plate 20 so as not to touch the hot plate 20.

Next, as shown in FIG. 6, the lifting mechanisms 29 rises to receive thetray plate 110 located on the hand part 4. After the tray plate 110 isreceived by the lifting mechanism 29, the transfer stage 28 returns thehand part 4 to the second chamber 3.

Next, as shown in FIG. 7, the lifting mechanisms 29 lowers to place thetray plate 110 on the hot plate 20. At this point, the gate valve 5 isclosed and the first chamber 2 and the second chamber 3 become isolatedfrom each other.

In this state, the carbonic acid vapor supply system 9 introducescarbonic acid vapor mixed with carrier gas such as reducing gas likehydrogen or carbon monoxide as well as inert gas like nitrogen into thefirst chamber 2. More specifically, open the valve 12 to introduce thecarrier gas into the sealed container 9 to cause bubbling, and open thevalve 10 carefully adjusting the opening to introduce carbonic acidvapor together with the carrier gas into the first chamber 2. Formicacid is used as the carbonic acid in the present embodiment.

The pressure inside the first chamber 2 is increased to a specifiedpressure with the introduction of the carbonic acid vapor and thecarrier gas. More specifically, the pressure of the carbonic acid vaporand the carrier gas is selected from a wide range of several Pa to 1×10⁵Pa considering the degree of oxidation of the surface of the processobject. The pressure of the carbonic acid vapor and the carrier gas canbe set by adjusting the degree of opening the valve 10 and the valve 6.In addition, The carbonic acid vapor exhausted by the exhaust pump 8(exhaust means) is collected by the carbonic acid collection part(collection mechanism) 15 provided or installed on the suction orexhaust side of the exhaust means for collecting vaporized carbonic acidto make it harmless.

In parallel with such an introduction of the carbonic acid vapor and thecarrier gas, the substrate 100 is heated by the hot plate 4. When thehot plate 20 is formed from a carbon plate-like member, it is possibleto heat the hot plate 20 by running an electric current through thecarbon plate-like member 20 itself. With the configuration of heatingthe carbon plate-like member 200 itself, it is possible to make it lesssusceptible to carbonic acid so that the corrosion resistance can beimproved. The hot plate 4 heats the substrate 100 until it reaches atemperature higher than the melting point of solder of the substrate100. For example, if the solder is Sn-3.5 Ag (melting point 221° C.), itis heated to a temperature of approximately 230° C.-250° C., which issuitable for soldering. If the solder is Pb-5 Sn (melting point 314°C.), it is heated to a temperature of approximately 330° C.-360° C.,which is suitable for soldering. From the standpoint of preventingvoids, the carbonic acid vapor should preferably be introduced beforethe temperature of the substrate 100 reaches the melting point of thesubstrate 100.

For example, after a specified time (e.g., 5-10 minutes), the current tothe hot plate 20 is shut off. After that, close the valves 10 and 12 tostop the supply of the carbonic acid vapor. Next, close the valve 15 tostop the operation of the exhaust pump 8, and open the valves 17 and 19to introduce nitrogen gas to replace the internal atmospheres of thefirst chambers 1 and 2 with nitrogen gas.

Next, the gate valve 5 is opened as shown in FIG. 8. With it, the rail27 is completed. The lifting mechanism 29 rises inside the first chamber2. The lifting mechanism 29 separates the tray plate 110 from the hotplate 20 while supporting the tray plate 110 on the hot plate 20. Incoordination with it, the transfer stage 28 travels from the secondchamber 3 to the first chamber 2 over the rail 27. The transfer stage(transfer means) 28 inserts the hand part 4 between the tray plate 110and the hot plate 20 while the tray plate 110 (or, the substrate 100itself if the substrate 100 is a single item) is being separated fromthe top of the hot plate 20 by means of the lifting mechanism 29. Thehand part 4 does to touch the hot plate 20 itself at this time.

Next, the lifting mechanism 29, 29 lowers and delivers the tray plate110 on the hand part 4. The hand part 4 is provided with the circulationpath 24 and water or other kinds of coolant is circulating inside thecirculating path 24. Therefore, the cooling of the substrate 100 startsimmediately after the tray plate 110 (or substrate 100) is placed on thehand part 4. Moreover, the hand part 4 does not cool the substrate 100via the hot plate 20 indirectly, but rather cools the substrate 100itself or the tray plate 110 directly so that it can cool them morerapidly.

Next, as shown in FIG. 9, the transfer part 22 transfers the tray plate110 from the first chamber 2 to the second chamber 3. In other words,since the hand part 4 that carries the process object in transferring itbetween the first chamber 2 and the second chamber 3 is also used as acooling plate, it can continue the forced cooling during the time whileit is transferring the process object. When the tray plate 110 returnsto the second chamber 3, the gate valve 5 is closed. The substrate 100whose soldering process is completed is taken out together with the trayplate 110 by opening the lid 21. If there is another substrate 100 to beprocessed, the system returns to the state shown in FIG. 4, and the trayplate 110 carrying the substrate 100 is loaded on the hand part 4 torepeat the soldering process.

The effect of using the apparatus for soldering process that does such aprocess will be described below. FIG. 10 is the temperature rise/fallcharacteristics of the solder processing apparatus 1 of the presentembodiment, while FIG. 11 is the temperature rise/fall characteristicsof the solder processing apparatus of the conventional type, providedhere for the comparison purpose, wherein the cooling plate is contactingclosely with the hot plate equipped with a heater. The measurements weremade, as shown in FIG. 12, by measuring temperatures at various points,i.e., point 1 through point 11 of the tray plate 110, placing the trayplate 110 made of carbon with a size of 300×300 mm and a thickness of 5mm on top of a carbon plate-like hot plate (carbon heater). As theprocess condition, the same condition shown in FIG. 13 is applied inboth the case of the apparatus for soldering process of the presentembodiment and in the case of the apparatus for soldering process of thecomparative example.

As shown in FIG. 11, in case of the apparatus for soldering process ofthe conventional type, it took approximately 16 minutes for thetemperature of the tray plate 110 to drop from 250° C. to 50° C., whileit required only 3 minutes or so for the temperature of the tray plate110 to drop from 250° C. to 50° C. in case of the apparatus forsoldering process of the present embodiment. Also, thanks to theadoption of the carbon plate-like member, the temperature distributionacross the measuring points 1 through 11 was uniform as the carbonplate-like member is heated by running a current through the carbonplate-like member itself.

As can be seen from the above, the use of the apparatus for solderingprocess of the present embodiment eliminates the need of indirectlycooling the process object via the hot plate equipped with the heatingmeans in case of rapid cooling the process object, so that a moreefficient rapid cooling becomes possible. In other words, by shorteningthe temperature lowering time, it increases the work speed and improvesthe productivity.

Although in the condition described above, it was assumed that theheating is to start from the room temperature, there is no need to coolthe hot plate 20 since the hand part 4 that functions as the coolingplate 20 does not touch the hot plate 20 in case of the apparatus forsoldering process of the present embodiment. Therefore, it is possibleto process the next process object maintaining the temperature of thehot plate 20 itself above the specified temperature, e.g., 70° C.-300°C. Thus, it can also shorten the temperature rising time as needed. Inother words, the prior method such as the one described in PatentDocument 1 requires to cool the hot plate in order to cool the processobject. In other words, although it is necessary to cool the processobject from the standpoint of preventing the oxidation of solder on theprocess object or to prevent the operator from burning, by the priormethod, it is necessary to cool even the hot plate. As a consequence, itis not necessary to lower the temperature of the hot plate 20 to theroom temperature in case of the apparatus for soldering process of thepresent embodiment, while it is necessary to lower the temperature ofthe hot plate to the normal temperature (20±15° C. according to JISstandard) in case of the prior method. Therefore, the heating time canbe shortened by raising the temperature of the hot plate 20 thatfunctions as the heating method to 70° C. or higher in advance.

FIG. 14 shows the temperature rise/fall characteristics in case theprocess object is delivered by the hand part 4 that functions as thecooling plate while maintaining the temperature of the hot plate 20itself at approximately 270° C. The vertical axis of FIG. 14 showstemperature (° C.) and the horizontal axis shows the elapsed time(minute). In FIG. 14, the dotted line represents the temperature of thehot plate 20, and solid lines represent temperatures at various points,i.e., point 1 through point 12, of the tray plate (process object) shownin FIG. 12. In a process as shown in FIG. 14, it is preferable to setthe target temperature to 230° C.-250° C. which is suitable forsoldering, and it is set to 250° C. in the present embodiment. In theexample shown in FIG. 14, the current through the hot plate 20 ismaintained to keep it in a heated condition even if no process object isplaced on it. The tray plate (process object) is placed on the hot plate20 while it is maintained at a set temperature of approximately 270° C.,higher than the target temperature. The instant when the tray plate isplaced on the hot plate 20, its temperature drops to approximately 230°C. for a moment. However, it goes back to the set temperature againbecause of the temperature control.

As shown in FIG. 14, it is possible to shorten the time needed to raisethe process temperature of the target object from the room temperatureto the target temperature (250° C.) by delivering the process objectwhile maintaining the temperature of the hot plate 20 in the vicinity ofthe target temperature of the hot plate 20 (preferably a temperaturerange higher than the target temperature). In the case shown in FIG. 14,the time that is needed to heat from the room temperature to the targettemperature (250° C.) is held within one minute. Compared to a case ofcontrolling the temperature of the hot plate 20 itself up and down asshown in FIG. 11, in which it takes about 5 minutes to raise from theroom temperature to the target temperature, the present embodiment cangreatly shorten the process time by delivering the process object whilemaintaining the temperature of the hot plate 20 approximately around thetarget temperature (preferably higher than the target temperature) asshown in FIG. 14.

Moreover, the temperature of the hot plate 20 does not overshoot if theprocess object is delivered while maintaining the temperature of the hotplate 20 itself at a vicinity of the target temperature (preferablyhigher than the target temperature) as shown in FIG. 14, in contrast tothe case of raising and lowering the temperature of the hot plate 20itself as shown in FIG. 11. Therefore, its control is easier.

As can be seen from FIG. 14, the apparatus for soldering process of thepresent embodiment eliminates the need of indirectly cooling the processobject via the hot plate equipped with the heating means in case ofrapidly cooling the process object, so that a more efficient rapidcooling becomes possible. In other words, by shortening the temperaturelowering time, it increases the work speed and improves theproductivity.

As can be seen above, the apparatus for soldering process of the presentembodiment has the following effects:

(1) The temperature lowering time can be shortened in case of rapidlycooling the process object compared to cooling the process objectindirectly via the hot plate equipped with the heating means.

(2) The next process object can be processed while maintaining thetemperature of the hot plate 20 itself at a high level. Therefore, itcan also shorten the temperature rising time as needed.

(3) Since the hand part 4 which is a component of the transfer means canbe used as a cooling plate, the transfer time can be utilized as aforced cooling period. Also, there is no need for providing the transfersystem and the cooling system as two independent machine components.

(4) Since the carbon plate-like member is used as the hot plate 20, thecarbon plate-like member can be heated by running a current through thecarbon plate-like member itself, so that the corrosion resistance can beimproved.

Second Embodiment

In the first embodiment above, a case of using the hand part 4 having acirculation path through which the cooling liquid is circulated. In thesecond embodiment, the hand part 4 does not have a circulation paththrough which the cooling liquid is circulated.

FIG. 15 shows a plan view of the apparatus for soldering processaccording to the second embodiment seen from above. The description ofthe configuration which is similar to that of the first embodiment isomitted. The hand part 4 of the apparatus for soldering processaccording to the present embodiment is preferably made of a materialwith a high thermal conductivity such as copper (398 W·m⁻¹·K⁻¹), andmore preferably made of a material with a thermal conductivity higherthan 100 W·m⁻¹·K⁻¹. In the present embodiment, the hand part 4 itselfdoes not have a circulation path through which the cooling liquid iscirculated.

As is shown in FIG. 15, a cooling part (forced cooling means) 30 thatforce-cools the hand part 4 is provided inside the second chamber 3. Thecooling part 30 can be constantly cooled by means of a cooling paththrough which cooling liquid is circulated as in the case of the handpart of the first embodiment, or can be cooled by air cooling or othermeans as the Peltier cooler.

The transfer mechanism (FIG. 15 only shows the rail part 27) can notonly move the hand part 4 back and forth freely between the firstchamber 2 (especially the hot plate 20) and the second chamber 3, itmoves the hand part 4 abutting upon the cooling part 30.

The apparatus for soldering process of the present embodiment operatesas follows. The moving mechanism causes the hand part 4 to move abovethe cooling part 30 and to abut against the cooling part 30. Abuttingagainst the cooling part 30, the hand part 4 is force-cooled. The movingmechanism then moves the hand part 4 away from the cooling part 30. Thehand part 4 moves from the second chamber 3 to the first chamber 2,receives the substrate 100 or the tray plate 110 on which the substrate100 is carried in the first chamber 2, and transfers the process objectby carrying the process object on it from the first chamber 2 to thesecond chamber 3. After the hand part 4 is heated to a high temperaturewhile carrying the heated process object on it, the hand part 4 is movedonto the cooling part 30 to be force-cooled. In other words, aftertaking out the heated process object from the first chamber 2, the handpart 4 is force-cooled by the cooling part 30 at least once until takingout the heated process object from the first chamber 1. Although thehand part 4 can be used to transfer the newly loaded process object fromthe second chamber 3 to the first chamber 2 in order to heat it, thereis no need to use the hand part 4 that is to be used as a cooling plateas well for loading it from the second chamber 3 to the first chamber 2,so that it is also possible to configure in such a way as to have aseparate hand for loading and the hand part 4 to be used as a coolingplate as well can be continuously force-cooled by the cooling part 30 inpreparation for the next take out process even during the loadingprocess executed by the other hand part. Since the receiving and thetransfer of the process object here is similar to that of the firstembodiment which was described referring to FIG. 8 and FIG. 9, detaildescriptions are omitted.

As the apparatus for soldering process of the present embodimenttransfers the process object using the hand part 4 after force-coolingit, it provides an effect of being able to utilize the transfer time asthe forced cooling period. Therefore, it provides a similar effect asthe first embodiment described above. There is no need to circulate thecooling liquid through the hand part 4 itself, so that there is no needto provide tubes for the cooling liquid in the moving parts. Therefore,equipment maintenance is easy in this case.

VARIANT EXAMPLE

In the heating process of the first embodiment, (a) evacuate the firstchamber 2 and the second chamber 3, and (b) while mixing the carrier gaswith carbonic acid vapor and introducing in the first chamber, heat thesubstrate in the atmosphere of the carrier gas and carbonic acid, andmelt the solder while conducting the reduction. Also, in the coolingprocess of the first embodiment, after (c) exhausting the mixed gas ofthe carrier gas and carbonic acid vapor from the first chamber 2, and(d) replacing the inside of the first chamber 2 and the second chamber 3with nitrogen gas, the process object is transferred from the firstchamber 2 to the second chamber 3 in the nitrogen atmosphere. Also, acase of constantly raising the temperature during the heating processwas described with reference to FIG. 13.

However, the present invention is not limited to this case. The hotplate can also be configured in such a manner, as shown in FIG. 16, asto maintain the process object at a reduction process temperature belowthe melting point of solder (preferably 130° C. or higher, morepreferably 150° C. or higher) for a few minutes. Maintaining such areduction process temperature can make it possible to sufficientlyexecute the reduction process of solder. According to the presentinvention, the hand part 4 that functions as the cooling plate does nottouch the hot plate 20 and the hot plate 20 does not need to be cooledeven in case of maintaining the reduction process temperature forpromoting the reduction process. Therefore, it is possible to keep thetemperature of the hot plate 20 itself at the reduction processtemperature.

Also, it is not necessarily required to raise its temperature in thecarbonic acid atmosphere prior to the reduction process. For example, itcan be heated in vacuum or in an atmosphere of inactive gas, such asnitrogen, until it reaches the reduction process temperature. In thiscase, carbonic acid can be introduced into the first chamber 2 afterreaching the reduction process temperature. It is advantageous to do soin raising the temperature in the inactive gas as it accelerates thetemperature rising speed.

Moreover, it was described in the first embodiment that the atmosphereof the first chamber 2 should be evacuated prior to convert it to themixture of the carrier gas and carbonic acid vapor. It is surelydesirable to evacuate the atmosphere of the first chamber 2 in order toreduce the oxygen amount, but this evacuation process can be omitted ifnecessary. For example, it is possible to replace the atmosphere of thefirst chamber 2 sufficiently with an inert gas such as nitrogen gas, andintroduce carbonic acid vapor into the chamber when the temperaturereaches the level high enough to promote the reduction process. In thiscase, the apparatus for soldering process is equipped with, in place ofthe evacuation means, an inert gas supply means to supply an inert gasinto the first chamber 2 and/or into the second chamber 3.

Moreover, the invention is not limited to a case of replacing thecarbonic acid atmosphere in the first chamber 2 and the second chamber 3with nitrogen gas after discharging it and lowering the temperature ofthe process object in the nitrogen gas atmosphere before taking it outas described in the first embodiment. Although it is surely preferableto lower the temperature of the process object prior to taking it outfrom the standpoint of expediting the temperature lowering speed, thetemperature can be lowered in vacuum for the purpose of avoiding theoxidation of the surface, if necessary, or can be so configured to movethe process object from the first chamber 2 to the second chamber 3without exhausting the carbonic acid atmosphere.

The above descriptions of the embodiments as well as a variation of thepresent invention are not in any way intended to limit the presentinvention.

For example, although the substrate to be soldered was described as anexample of the process object and the apparatus for soldering processwas described as an example of the apparatus for thermal meltingprocess, the present invention is not limited by those examples. Thepresent invention can be applied to any thermal melting process ofsolder concerning any process object including solder. For example, itcan be applied to a solder ball forming apparatus for forming solderballs by means of melting solder, or any other apparatus for thermalmelting process. The substrate here is not limited to the substrate tobe soldered.

Although the apparatus for thermal melting process having a firstchamber and a second chamber was described in the above, the inventionis not limited to it. With respect to the apparatus for thermal meltingprocess for conducting a thermal melting process on process objectsincluding solder in an atmosphere containing carbonic acid vapor, thehand part of the transfer means that is used to take out the processobject from the first chamber and transfer it can be used as a coolingplate as well. The apparatus for thermal melting process can have morethan three chambers. For example, it can have a loading side chamber forloading the process object prior to heating into the first chamber, anda discharge side chamber for removing the process object from the firstchamber after the heating process. In this case, the hand part fortransferring the process object after heating among a plurality of handparts can be used as a cooling plate.

That is to say, the present invention is applicable to any apparatus forthermal melting process that thermally melts objects including solder inan atmosphere containing carbonic acid vapor, and that has a hand partfor transferring the thermally melted process object which is used as acooling plate as well.

Any parts of the present invention can be added, deleted, or modifiedwithin the scope of the claims.

The invention claimed is:
 1. A thermal melting apparatus for conductinga thermal melting process on process objects including solder in anatmosphere containing carbonic acid vapor, wherein, said apparatuscomprises: a first chamber for conducting the thermal melting process onthe process object including solder; a second chamber connected to thefirst chamber via a valve capable of opening and closing; a carbonicacid supply means for supplying the carbonic acid to the first chamber;a heating means provided in the first chamber for heating the processobject; a transfer means, which is movably provided between the firstchamber and the second chamber, the transfer means including a hand parton which the process object is placed, the hand part having an internalcirculation path or an external circulation path through which a coolingmedium can flow, wherein the hand part is also used as a cooling plateto cool the process object; and a forced cooling means for forcedlycooling the hand part.
 2. The apparatus of claim 1, wherein the handpart is provided with a circulation path for circulating a coolingliquid.
 3. The apparatus of claim 1 wherein said forced cooling meansforce-cools the hand part abutted thereto and provided in the secondchamber, and wherein the hand part cooled by the forced cooling meanscarries the process object to transfer it from the first chamber to thesecond chamber.
 4. The apparatus of claim 3, wherein the transfermeanings comprise a transfer mechanism that transfers the hand partfreely forward or backward.
 5. The apparatus of claim 4, wherein theheating means is a carbon plate-like member that carries the processobject, and heats the process object by apply electric current to thecarbon plate-like member.
 6. The apparatus of claim 5 furthercomprising: a lifting mechanism that raises or lowers the process objectplaced on the heating means, wherein the hand part is inserted betweenthe process object and the heating means after the process object islifted of the top surface of the heating means by the lifting mechanism.7. The apparatus of claim 6, wherein the carbonic acid supply meansfurther comprises: a container for storing carbonic acid liquid; and asupply tube for communicating with the container and for supplyingcarrier gas to be mixed with carbonic acid vapor generated in thecontainer.
 8. The apparatus of claim 6, wherein the carbonic acid supplymeans further comprises: a supply tube to supply the carbonic acidliquid to the first chamber; and a carbonic acid heating means that isprovided in the first chamber to cause the carbonic acid liquid toevaporate.
 9. The apparatus of claim 8 further comprising: one or moreexhaust means for reducing the pressures in the first chamber and thesecond chamber.
 10. The apparatus of claim 9 further comprising: acollection mechanism provided or installed on the suction side or theexhaust side of the exhaust means to collect the evaporated carbonicacid.
 11. The apparatus of claim 8 further comprising: an inert gassupply means for supplying inert gas in the first chamber or the secondchamber.
 12. The apparatus of claim 11, wherein the process object is asubstrate to be soldered, and the thermal melting process is a solderingprocess.
 13. The apparatus of claim 12, wherein the substrate to besoldered is a pair of chips including at least a chip where a pluralityof solder bumps are formed on the surface thereof, and the solderingprocess is a flip-chip bonding process for jointing the pair of chipsvia the solder bumps themselves or via the solder bumps with electrodes.14. The apparatus of claim 13, wherein the substrate consists of a chipand a wafer where a plurality of solder bumps are formed on the surfacethereof, or a plurality of wafers where a plurality of solder bumps isformed on the surface thereof.
 15. The apparatus of claim 8, wherein thehand part, which is also used as the cooling plate, is provided there tocarry the process object without touching the heating means; and thetemperature of the heating means is raised to 70° C. or higher inadvance in order to shorten the heating time.